Image display apparatus, image display method and computer-readable recording medium storing image display program

ABSTRACT

An image display apparatus in which image signals of a plurality of primary colors are transformed by an image processing section into color space that includes lightness and chromaticity. When the chromaticity (color vividness) in this color space is being corrected, the correction method is changed in accordance with the optical modulation state of the display apparatus. If optical modulation is performed, then correction is made to lower the chromaticity, while correction is made to raise the chromaticity when there is no optical modulation.

This is a Division of application Ser. No. 10/449,494 filed Jun. 2,2003. The entire disclosure of the prior application is herebyincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image display apparatus, an imagedisplay method, and a computer readable recording medium storing animage display program.

2. Description of Related Art

In recent years, the performance required by various fields in an imagedisplay apparatus has increased as informational technology hasadvanced. Among such image display apparatuses, a liquid crystal displaythat allows optical characteristics to be changed by the electricalcontrol of the orientation of liquid crystal molecules, that has lowpower consumption, that is flat-panel shaped, and that does not strainthe eyes and the like has become particularly sought after. Furthermore,a projection type of liquid crystal display (liquid crystal projector)in which images emitted from an optical system that uses liquid crystallight valves are transmitted through a projection lens and projected inenlargement on a screen is becoming widely used as one form of liquidcrystal display.

In this projection type of liquid crystal display, liquid crystal lightvalves are used as an imager, however, due to leakage light and straylight, the brightness range (dynamic range) that can be displayed isnarrow, and in some cases an improvement in image quality is difficultto achieve. Because of this, the dynamic range control method has beenproposed for the improvement of the contrast of the image, which changesthe flux of light irradiated into the light valves (imager) inaccordance with image signals and expands data representing thebrightness level of an image displayed on the light valve. However, ifan image displayed on a light valve is expanded, problems occur such asthe RGB ratio (balance) of a projected image deteriorating, and thecolor (i.e., the vividness of the color) of the projected imagechanging.

The present invention was conceived in view of the above circumstances,and it is an object thereof to provide an image display apparatus, animage display method, and a computer readable recording medium storingan image display program that enables the dynamic range of a displayedimage (i.e., the range of displayable brightness) to be altered inaccordance with image signals of a displayed image, which are theessence of an image being displayed, without changing the ratios ofimage signals of a plurality of primary colors.

SUMMARY OF THE INVENTION

The first aspect of the present invention is an image display apparatusthat adjusts a displayed image by changing a flux of light and that hasan expansion device that expands image signals of a plurality of primarycolors of a displayed image based on a predetermined expansioncoefficient, an image signal transformation device that transforms imagesignals expanded by the expansion device into color space that includeschromaticity and lightness, a correction device that correctschromaticity in the color space; and a color space transformation devicethat transforms color space that includes a chromaticity corrected bythe correction device into image signals of a plurality of primarycolors.

Moreover, the first aspect of the present invention is an image displaymethod that adjusts a displayed image by changing a flux of light, andthat has a first step of expanding image signals of a plurality ofprimary colors of a displayed image based on a predetermined expansioncoefficient; a second step of transforming image signals expanded in thefirst step into color space that includes chromaticity (saturation) andlightness (value), a third step of correcting chromaticity in the colorspace, and a fourth step of transforming color space that includes achromaticity corrected in the third step into image signals of aplurality of primary colors.

The second aspect of the present invention is an image display apparatusthat adjusts a displayed image by changing a flux of light, and that hasan image signal transformation device that transforms image signals of aplurality of primary colors of a displayed image into color space thatincludes chromaticity and lightness, a correction device that correctschromaticity in the color space, an expansion device that expands colorvalue in color space that has been transformed by the image signaltransformation device based on a predetermined expansion coefficient,and a color space transformation device that transforms color space thatincludes a color value expanded by the expansion device and thecorrected chromaticity into image signals of a plurality of primarycolors.

Moreover, the second aspect of the present invention is an image displaymethod that adjusts a displayed image by changing a flux of light, andthat has a first step of transforming image signals of a plurality ofprimary colors of a displayed image into color space that includeschromaticity and lightness, a second step of correcting chromaticity inthe color space, a third step of expanding color value in color spacethat has been transformed in the first step based on a predeterminedexpansion coefficient; and a fourth step of transforming color spacethat includes a color value expanded in the third step and the correctedchromaticity into image signals of a plurality of primary colors.

In the present invention, a transformation into HSV space and atransformation into Yuv space can be held up as examples oftransformations of image signals into color space by the image signaltransformation device.

When the image signals are transformed into HSV space, the correctiondevice corrects S signals, which are signals representing colorvividness. When the image signals are transformed into Yuv space, thecorrection device corrects u signals and v signals, which are signalsrepresenting color.

Because the image display apparatus and image display method of thefirst aspect transform expanded image signals of a plurality of primarycolors into color space that includes chromaticity and lightness, and,after correcting the chromaticity, then transforms the color space backinto image signals of a plurality of primary colors, the dynamic rangeof a displayed image can be altered without changing the ratios of theimage signals of the plurality of primary colors.

Because the image display apparatus and image display method of thesecond aspect transform image signals of a plurality of primary colorsinto color space that includes chromaticity and lightness, and, afterexpanding the color value and correcting the chromaticity, thentransforms the color space back into image signals of a plurality ofprimary colors, the dynamic range of a displayed image can be alteredwithout changing the ratios of the image signals of the plurality ofprimary colors.

Furthermore, in the first and second aspects, in the transformation intoHSV space by the image signal transformation device, the correctioncalculation is a simple one, enabling the speed of the processing to beincreased. In the transformation into Yuv space by the image signaltransformation device, because the processing to make the transformationinto Yuv space is performed on the basis of a predetermined formula, thespeed of the transformation processing can be increased, enabling theprocessing speed of the overall correction processing to be increased.

The third aspect of the present invention is an image display apparatusthat adjusts a displayed image by changing a flux of light, and that hasan offset processing device that performs offset processing on imagesignals of a plurality of primary colors of a displayed image based onoffset values, an expansion device that expands image signals that haveundergone offset processing by the offset processing device based on apredetermined expansion coefficient, an image signal transformationdevice that transforms image signals expanded by the expansion deviceinto color space that includes chromaticity and lightness, a correctiondevice that corrects chromaticity in the color space; and a color spacetransformation device that transforms color space that includes achromaticity corrected by the correction device into image signals of aplurality of primary colors.

Moreover, the third aspect of the present invention is an image displaymethod that adjusts a displayed image by changing a flux of light, andthat has a first step of performing offset processing on image signalsof a plurality of primary colors of a displayed image based on offsetvalues, a second step of expanding image signals that have undergoneoffset processing in the first step based on a predetermined expansioncoefficient, a third step of transforming image signals expanded in thesecond step into color space that includes chromaticity and lightness, afourth step of correcting chromaticity in the color space, and a fifthstep of transforming color space that includes a chromaticity correctedin the fourth step into image signals of a plurality of primary colors.

The fourth aspect of the present invention is an image display apparatusthat adjusts a displayed image by changing a flux of light, and that hasan image signal transformation device that transforms image signals of aplurality of primary colors of a displayed image into color space thatincludes chromaticity and lightness, a correction device that correctschromaticity in the color space, an offset processing device thatperforms offset processing on color value in color space that has beentransformed by the image signal transformation device based on offsetvalues, an expansion device that expands color value in color space thathas undergone offset processing by the offset processing device based ona predetermined expansion coefficient, and a color space transformationdevice that transforms color space that includes color value that hasbeen expanded by the expansion device and chromaticity that has beencorrected by the correction device into image signals of a plurality ofprimary colors.

Moreover, the fourth aspect of the present invention is an image displaymethod that adjusts a displayed image by changing a flux of light, andthat has a first step of transforming image signals of a plurality ofprimary colors of a displayed image into color space that includeschromaticity and lightness, a second step of correcting chromaticity inthe color space, a third step of performing offset processing on colorvalue in color space that has been transformed in the first step basedon offset values; a fourth step of expanding color value in color spacethat has undergone offset processing in the third step based on apredetermined expansion coefficient, and a fifth step of transformingcolor space that includes color value that has been expanded in thefourth step and chromaticity that has been corrected in the second stepinto image signals of a plurality of primary colors.

The image display apparatus and image display methods of the third andfourth aspects ensure that there is no change to the color vividness ofimage signals by the offset processing device performing offsetprocessing based on an offset value.

Here, the value of substantially the darkest portion from the image datais used for the offset value. The term “offset processing” refers to thesubtraction or addition of an offset value to an image signal so as toensure there is no change to the color vividness of that image signal.

In the image display apparatus and image display methods of the thirdand fourth aspects, because offset processing is performed on imagesignals before they are transformed into color space, or on color valuein color space after image signals have been transformed into colorspace, vivid portions of the image signals stand out. Therefore, theeffect when chromaticity is corrected can be manifested even moreclearly.

The fifth aspect of the present invention is an image display apparatusthat adjusts a displayed image by changing a flux of light, and that hasa correction device that corrects chromaticity in image signals based ona predetermined calculation formula for each image signal of a pluralityof primary colors of a displayed image.

Moreover, the fifth aspect of the present invention is an image displaymethod that adjusts a displayed image by changing a flux of light, andthat has the step of correcting expansion and chromaticity on imagesignals based on a predetermined calculation formula for respectiveimage signals of a plurality of primary colors of a displayed image.

Because the image display apparatus and image display method of thefifth aspect perform chromaticity correction directly by calculationusing a predetermined calculation formula, the labor required totransform image signals to color space and then transform the colorspace back to image signals can be shortened, and an increase in thespeed of the correction processing can be achieved.

The sixth aspect of the present invention is an image display apparatusthat adjusts a displayed image by changing a flux of light, and that hasa transformation device that expands respective image signals of aplurality of primary colors of a displayed image based on apredetermined transformation table, and a correction device thatcorrects chromaticity of image signals of each color that have beentransformed by the transformation device.

Moreover, the sixth aspect of the present invention is an image displaymethod that adjusts a displayed image by changing a flux of light, andthat has a first step of performing expansion or offset processing onrespective image signals of a plurality of primary colors of a displayedimage based on a predetermined transformation table, and a second stepof correcting chromaticity in image signals of each color that have beentransformed in the first step.

In the image display apparatus and image display method of the sixthaspect, by using a transformation table complicated expansion processingis made possible and the image representation width can be broadened.

It is also possible for the image display apparatus of the presentinvention to further have a detection device that detects a flux ofleakage light, and for the correction device to make corrections basedon the flux of leakage light.

The term “flux of leakage light” refers to the flux of light that isdisplayed when the light valve is set such that the display is at itsdarkest setting.

By employing this structure, because the correction device is able totake the flux of leakage light also into consideration when making acorrection, it is able to correct chromaticity more correctly.

Moreover, it is also possible to employ a structure in which theexpansion device makes an expansion based on a predetermined expansioncoefficient, and further has a prediction device that predicts thechromaticity based on at least one of the offset value and the expansioncoefficient and on the flux of leakage light, and in which thecorrection device makes a correction based on a chromaticity predictedby the prediction device.

By employing this structure accurate chromaticity correction can be madebecause the correction device makes a correction based on a chromaticitypredicted by the prediction device.

Moreover, it is also possible to employ a structure further having aselection device that selects one of a plurality of chromaticitiespredicted by the prediction device, and the correction device makes acorrection based on a chromaticity selected by the selection device.

By employing this structure correction can be made in accordance with auser's specifications because the method of correction by the correctiondevice can be selected by the selection device.

Examples of the plurality of chromaticities predicted by the predictiondevice include chromaticity predicted on the basis of expanded imagesignals and chromaticity predicted on the basis of unexpanded imagesignals.

The correction by the correction device may be a correction to raise thecolor vividness or a correction to lower the color vividness. The term“correction to raise the color vividness” refers to a correction tomatch the color vividness to a chromaticity predicted on the basis ofexpanded image signals. The term “correction to lower the colorvividness” refers to a correction to match the color vividness to achromaticity predicted on the basis of unexpanded image signals.

The seventh aspect of the present invention is a computer-readablerecording medium storing an image display program for adjusting adisplayed image by changing a flux of light, the program beingexecutable on a computer, and having an expansion function that expandsimage signals of a plurality of primary colors of a displayed imagebased on a predetermined expansion coefficient, an image signaltransformation function that transforms image signals expanded by theexpansion function into color space that includes chromaticity andlightness, a correction function that corrects chromaticity in the colorspace; and a color space transformation function that transforms colorspace that includes a chromaticity corrected by the correction functioninto image signals of a plurality of primary colors.

The eighth aspect of the present invention is a computer-readablerecording medium storing an image display program for adjusting adisplayed image by changing a flux of light, the program beingexecutable on a computer, and having an image signal transformationfunction that transforms image signals of a plurality of primary colorsof a displayed image into color space that includes chromaticity andlightness, a correction function that corrects chromaticity in the colorspace, an expansion function that expands color value in color spacethat has been transformed by the image signal transformation functionbased on a predetermined expansion coefficient, and a color spacetransformation function that transforms color space that includes acolor value expanded by the expansion function and the correctedchromaticity into image signals of a plurality of primary colors.

The ninth aspect of the present invention is a computer-readablerecording medium storing an image display program for adjusting adisplayed image by changing a flux of light, the program beingexecutable on a computer, and having an offset processing function thatperforms offset processing on image signals of a plurality of primarycolors of a displayed image based on offset values, an expansionfunction that expands image signals that have undergone offsetprocessing in the offset processing function based on a predeterminedcoefficient, an image signal transformation function that transformsimage signals expanded by the expansion function into color space thatincludes chromaticity and lightness, a correction function that correctschromaticity in the color space, and a color space transformationfunction that transforms color space that includes a chromaticitycorrected by the correction function into image signals of a pluralityof primary colors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural view showing an example of a projectiontype display apparatus;

FIG. 2 is a block diagram showing the structure of a drive circuit ofthe projection type display apparatus of the first embodiment;

FIG. 3 is a block diagram showing the structure of an image processingsection when image signals are transformed into HSV space; and

FIG. 4 is a view showing an HSV color space;

FIG. 5 is a block diagram showing a variant example of the imageprocessing section shown in FIG. 3;

FIG. 6 is a block diagram showing the structure of an image processingsection when image signals are transformed into Yuv space;

FIG. 7 is a block diagram showing a variant example of the imageprocessing section shown in FIG. 6;

FIG. 8 is a block diagram showing the structure of a drive circuit ofthe projection type display apparatus of the second embodiment;

FIG. 9 is a block diagram showing the structure of the image processingsection of the second embodiment when image signals are transformed intoHSV space;

FIG. 10 is a block diagram showing a variant example of the imageprocessing section shown in FIG. 9;

FIG. 11 is a block diagram showing the structure of the image processingsection of the second embodiment when image signals are transformed intoYuv space;

FIG. 12 is a block diagram showing a variant example of the imageprocessing section shown in FIG. 11;

FIG. 13 is a block diagram showing the structure of an image processingsection of the third embodiment;

FIG. 14 is a block diagram showing the structure of a drive circuit ofthe projection type display apparatus of the fourth embodiment;

FIG. 15 is a view showing an example of a transformation table;

FIG. 16 is a block diagram showing the structure of the image processingsection of the fourth embodiment when a transformation table is used;

FIG. 17 is a block diagram showing the structure of the image processingsection of the fourth embodiment when image signals are transformed intoHSV space;

FIG. 18 is a block diagram showing a variant example of the imageprocessing section shown in FIG. 17;

FIG. 19 is a block diagram showing the structure of a drive circuit whenencoded image signals are input; and

FIG. 20 is a view showing a variant example of the drive circuit shownin FIG. 19.

DETAILED DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the image display apparatus, image displaymethod, and computer readable recording medium storing an image displayprogram of the present invention will now be described in detail whilereferring to FIGS. 1 through 20.

In this description, a projection monitor with three light valves thatis provided with a liquid crystal light valve for each different RGBcolor is used as an example of an image display apparatus that uses theimage display method of the present invention.

FIG. 1 is a schematic structural view showing an example of a projectiontype display apparatus.

As is shown in FIG. 1, the projection type display apparatus is providedwith a light source 510, an optical modulator 26, dichroic mirrors 513and 514, reflection mirrors 515, 516, and 517, relay lenses 518, 519,and 520, a liquid crystal light valve for red light 522, a liquidcrystal light valve for green light 523, a liquid crystal light valvefor blue light 524, a cross dichroic prism 525, and a projection lenssystem 526.

The optical modulator 26 may be formed, for example, by a liquid crystalpanel with variable transmissivity.

The light source 510 is formed by a lamp 511, such as an ultra-highpressure mercury vapor lamp, and a reflector 512 that reflects lightfrom the lamp 511. The optical modulator 26 that adjusts the flux oflight from the light source 510 is positioned between the light source510 and the dichroic mirror 513.

The blue and green light reflection dichroic mirror 513 allows red lightfrom white light from the light source 510 to be transmitted, andreflects blue light and green light. The transmitted red light isreflected by the reflection mirror 517 and is irradiated into the liquidcrystal light valve for red light 522.

The green light that is reflected by the dichroic mirror 513 isreflected by the dichroic mirror 514 for reflecting green light, and isirradiated into the liquid crystal light valve for green light 523.

The blue light that is reflected by the dichroic mirror 513 istransmitted through the dichroic mirror 514, and is irradiated into theliquid crystal light valve for blue light 524 via a relay system 521formed by the relay lens 518, the reflection mirror 515, the relay lens519, the reflection mirror 516, and the relay lens 520.

The light of the three colors modulated by the respective liquid crystallight valves 522, 523, and 524 is irradiated into the cross dichroicprism 525. This prism is formed by bonding together four rectangularprisms. On the inner surfaces thereof a dielectric multilayer film thatreflects red light and a dielectric multilayer film that reflects bluelight are provided in a cruciform pattern. The light of the three colorsis then synthesized by these dielectric multilayer films to form lightrepresenting a color image. The synthesized light is projected onto ascreen 527 by the projection lens system 526, which is a projectionoptical lens system, so that an enlarged image is displayed.

Image processing sections (not shown in FIG. 1) that performpredetermined image processing on the light of each color based on imagesignals are connected to each of the liquid crystal light valves 522,523, and 524. Image signals that have undergone predetermined imageprocessing in the image processing sections are supplied to therespective liquid crystal light valves 522, 523, and 524 via light valvedrivers. The projection type display apparatus of the present inventiondisplays an image on the basis of predetermined image processingperformed in the image processing sections.

Here, the image display method of the first through fourth embodimentsaccording to the projection type display apparatus of the presentembodiment will be described.

FIG. 2 is a block diagram showing the structure of a drive circuit ofthe projection type display apparatus of the first embodiment.

Firstly, image signals are input into an image processing section 21 andan image analysis section 24. In the image analysis section 24, theimage signals are analyzed and an expansion coefficient is calculated.This is then supplied to the image processing section 21 as an imagecontrol signal.

The image analysis section 24 also controls an optical modulator driver25 based on optical modulation control signals. The optical modulatordriver 25 controls the optical modulator 26. The optical modulatordriver 25 changes the quantity of illumination light from the lightsource 510 in accordance with whether or not there is an image signalexpansion supplied to the respective light valves 522, 523, and 524 bythe image processing section 21. As a result, it is possible to achievesmooth gradation expression while enlarging the brightness range of adisplayed image. In the projection type display apparatus of the presentinvention, as a result of the above described operation, it is possibleto broaden the dynamic range and achieve an improvement in imagequality.

When, for example, the image signals supplied to each of the liquidcrystal light valves 522, 523, and 524 are expanded, the opticalmodulator driver 25 controls the optical modulator 26 such that thequantity of illumination light is decreased.

On the other hand, when RGB signals are input into the image processingsection 21, the RGB signals are transformed into either HSV space or Yuvspace, which are color spaces. After performing predetermined imageprocessing on the image signals that have been transformed into colorspaces (HSV spaces or Yuv spaces), the image processing section 21performs a back transformation on the color spaces so as to restore themto RGB signals. The RGB signals that have been transformed back by theimage processing section 21 are input into a light valve driver 22 foreach color light. The light valve driver 22 controls a light valve 23for each color light based on the back transformed RGB signals.

Next, a detailed description will be given while referring to FIG. 3 ofthe image processing by the image processing section 21 of the firstembodiment.

FIG. 3 is a block diagram showing the structure of the image processingsection 21 when image signals are transformed into HSV space.

As is shown in FIG. 3, the image processing section 21 is provided withan expansion section 31, an image signal transformation section 32, achromaticity correction section 33, a chromaticity prediction section34, and a color space transformation section 35.

The expansion section (i.e. the expansion device) 31 performs expansionprocessing on image signals in accordance with an expansion coefficientsupplied from the image analysis section 24.

The image signal transformation section (i.e., the image signaltransformation device) 32 transforms RGB signals that have undergoneexpansion processing into HSV space, which is a color space. This HSVspace is a color space such as that shown in FIG. 4, with the H signalsexpressing hue, the S signals expressing chromaticity (color vividness),and the V signals expressing lightness (color value).

A memory/sensor section (detecting device) 201 is positioned on theemission side of the light valve 23. The memory/sensor section 201detects the flux of leakage light from the light valve 23 and recordsthe detected flux of leakage light. The term “flux of leakage light”refers to the brightness on the screen when the image signal is 0. Morespecifically, it refers to the flux of light that leaks onto the screeneven when the respective liquid crystal valves 522, 523, and 524 are allin a dark display state, and in spite of the fact that the flux of lightfrom the light source 510 has been shut out by an optical modulator.

This flux of leakage light may be measured during the pre-shippinginspection and stored as a default value. It is also possible for theflux of leakage light to be measured when the power of the projectiontype display apparatus is turned on or during start up of the projectiontype display apparatus, and for this measurement to be stored.

A console section (selection device) 202 is where a user selectscorrection parameters such as whether to raise or lower the chromaticitycorrection to the chromaticity predicted by the chromaticity predictionsection 34.

The chromaticity prediction section (prediction device) 34 predicts thechromaticity of a projected image signal based on expansion coefficientssupplied from the image analysis section 24 and fluxes of leakage lightsupplied from the memory/sensor section 201.

The chromaticity correction section (correction device) 33 performschromaticity correction on color vividness signals (S signals) among theHSV space based on chromaticity prediction values predicted by thechromaticity prediction section 34.

The color space transformation section (color space transformationdevice) 35 performs back transformation to restore HSV space to RGBsignals.

A description will now be given of the correction processing of theimage processing section 21 when a transformation has been made into HSVspace using specific numerical values. Here, as an example, adescription is given of chromaticity correction when the image signals(R, G, B) are (10, 50, 20), the flux of leakage light is 10, and theexpansion coefficient is 2. It is assumed that gamma valve is 1.0.

Firstly, when normal image signals are transformed into HSV space, theyare as is shown in Formula (1) below. Here, the chromaticity predictionsection 34 transforms image signals, to which the flux of leakage lightof 10 has been added, into HSV space, and predicts the chromaticity. Asis shown in Formula (2), here, the chromaticity is predicted to be 170.

(1) Original signal

(R, G, B)=(10, 50, 20). At this time (H, S, V)=(135, 204, 50)

(2) After taking flux of leakage light into consideration

(R, G, B)=(20, 60, 30). At this time (H, S, V)=(135, 170, 60)

Next, the chromaticity prediction section 34 predicts chromaticity foran image signal when the expansion coefficient is an expansion factor of2. The image signal before the expansion can be expressed as is shown inFormula (3) to provide the same formula as Formula (1) above.

(3) Original signal

(R, G, B)=(10, 50, 20). At this time (H, S, V)=(135, 204, 50)

Next, if the image signal is expanded by a factor of 2, the chromaticityprediction after the twofold expansion is shown below in Formula (4).

(4) Expansion

(R, G, B)=(20, 100, 40). At this time (H, S, V)=(135, 204, 100)

If the image signals resulting when the flux of leakage light of 10 isadded to the image signals that have undergone the twofold expansion ofFormula (4) are transformed into HSV space, and the chromaticity ispredicted, then they are as shown in Formula (5).

(5) After taking flux of leakage light into consideration

(R, G, B)=(30, 110, 50). At this time (H, S, V)=(135, 185, 110)

Next, because there was an expansion factor of 2, if the image signalsof Formula (5) are modulated by ½ as their optical modulation (lightreduction, dimming) factor, then they are as shown in Formula (6).

(6) Optical modulation (×½)

(R, G, B)=(15, 55, 25). At this time (H, S, V)=(135, 185, 55)

Here, as is shown in Formula (6), the chromaticity when expansion factoris 2 is predicted to be 185. The chromaticity correction section 33performs chromaticity correction based on the values of the chromaticity(here, 170 and 185) predicted by the chromaticity prediction section 34.

A description will now be given of the chromaticity correction performedby the chromaticity correction section 33. Chromaticity correction is amethod of either lowering color space chromaticity to the chromaticitypredicted for when there is no expansion, or raising the color spacechromaticity to the chromaticity predicted for when there is anexpansion.

Firstly, a description will be given of when correction is performed bymaking an adjustment to lower the chromaticity to 170.

In the above Formula (4), if S′ is 185, then the image signals are asshown below.

(H, S′, V)=(135, 185, 100). At this time (R, G, B)=(27, 100, 45).

If this (R, G, B)=(27, 100, 45) is given a flux of leakage light of 10and an optical modulation factor of ½, then

(5′) After taking flux of leakage light into consideration

(R, G, B)=(37, 110, 55). At this time (H, S, V)=(135, 170, 110)

(6′) Optical modulation (×½)

(R, G, B)=(18, 55, 28). At this time (H, S, V)=(135, 170, 55)

As is shown in Formula (6′), adjustment has been made to lower thechromaticity to 170.

Next, a description will be given of when correction is performed bymaking an adjustment to raise the chromaticity to 185.

In the above Formula (1), if S′=204×185/170=223, then the image signalsare as shown below in Formula (1′).

(1′) Original signal

(H, S′, V)=(135, 223, 50). At this time (R, G, B)=(6, 50, 17)

If this (R, G, B)=(6, 50, 17) is given a flux of leakage light of 10 andan optical modulation factor of ½, then

(2′) After taking flux of leakage light into consideration

(R, G, B)=(16, 60, 27). At this time (H, S, V)=(135, 185, 60)

As is shown in Formula (2′), adjustment has been made to raise thechromaticity to 185.

When transforming image signals into HSV space and correctingchromaticity in this manner, the calculation for the chromaticitycorrection is simple and an increase in processing speed can beachieved.

FIG. 5 is a block diagram showing a variant example of the imageprocessing section 21 of FIG. 3. Note that the same numbers are given tocomponent elements that are identical to those appearing in FIG. 3, anda description thereof is omitted.

In the image processing section 21 shown in FIG. 5, a structure isemployed in which the expansion processing by the expansion section 31is only performed on V signals after transformation thereof by the imagesignal transformation section 32.

Because expansion processing is performed on V signals, which indicatebrightness value information after transformation into color space, itis possible to reduce the size of the circuit structure, and furtherincrease the processing speed. FIG. 6 is a block diagram showing thestructure of the image processing section 21 when image signals aretransformed into Yuv space. Note that the same numbers are given tocomponent elements that are identical to those appearing in FIG. 3, anda description thereof is omitted.

As is shown in FIG. 6, the image processing section 21 is provided withan expansion section 31, an image signal transformation section 320, a usignal correction section 330, a v signal correction section 331, achromaticity prediction section 34, and a color space transformationsection 350.

The image signal transformation section 320 transforms RGB signals thathave been expanded into Yuv space, which is a color space. Thistransformation into Yuv space is performed on the basis oftransformation formulas such as those shown in Formula Group A below. InYuv space the Y signals express brightness and the u signals and vsignals express chromaticity, and from these it is possible to expresschromaticity (color vividness).

$\begin{matrix}{{\begin{pmatrix}Y \\u \\v\end{pmatrix} = {\begin{pmatrix}0.299 & 0.587 & 0.114 \\{- 0.147} & {- 0.289} & 0.436 \\0.615 & {- 0.515} & {- 0.100}\end{pmatrix}\begin{pmatrix}r \\g \\b\end{pmatrix}}}{\begin{pmatrix}r \\g \\b\end{pmatrix} = {\begin{pmatrix}1 & 0 & 1.14 \\1 & {- 0.394} & {- 0.581} \\1 & 2.03 & 0\end{pmatrix}\begin{pmatrix}Y \\u \\v\end{pmatrix}}}{H = {\tan^{- 1}\left( {v/u} \right)}}{S = {\sqrt{u^{2} + v^{2}}/Y}}} & \left\lbrack {{Formula}\mspace{14mu}{group}\mspace{14mu} A} \right\rbrack\end{matrix}$

The chromaticity prediction section 34 predicts the chromaticity ofprojected image signals based on expansion coefficients supplied fromthe image analysis section 24 and quantities of escaped light that aresupplied from the memory/sensor section 201.

The u signal correction section 330 performs chromaticity correction ofu signals, which are color vividness signals, based on chromaticityprediction values predicted by the chromaticity prediction section 34.In the same way, the v signal correction section 331 performschromaticity correction of v signals, which are color vividness signals,based on chromaticity prediction values predicted by the chromaticityprediction section 34.

The color space transformation section 350 performs back transformationto restore Yuv space to RGB signals.

A description will now be given of the correction processing of theimage processing section 21 when a transformation has been made into Yuvspace using specific numerical values. Here, as an example, adescription is given of u signal correction and v signal correction whenthe image signals (R, G, B) are (10, 50, 20), the flux of leakage lightis 10. It is assumed that gamma valve is 1.0.

Firstly, when normal image signals are transformed into Yuv space basedon Formula group A, a formula such as Formula (7) below is obtained.Here, if image signals, to which the flux of leakage light of 10 hasbeen added, are also transformed into Yuv space based on Formula groupA, they are as shown in Formula (8) below.

(7) Original signals

(R, G, B)=(10, 50, 20). At this time (Y, u, v)=(35, −7.2, −22)

(8) After taking flux of leakage light into consideration

(R, G, B)=(20, 60, 30). At this time (Y, u, v)=(45, −7.2, −22)

For Yuv space, as is shown by Formula group A, the chromaticity isexpressed by (u²×v²)^(1/2)/Y. As a result, the chromaticity predictionsection 34 predicts that the chromaticity S₍₂₎ with the flux of leakagelight taken into consideration will equal 0.510.

Next, the chromaticity prediction section 34 predicts chromaticity foran image signal when the expansion coefficient is an expansion factor of2. The image signal before the expansion can be expressed as is shown inFormula (9) to provide the same formula as Formula (7) above.

(9) Original signal

(R, G, B)=(10, 50, 20). At this time (Y, u, v)=(35, −7.2, −22)

Next, if the image signal is expanded by a factor of 2, the chromaticityprediction after the twofold expansion is shown below in Formula (10).

(10) Twofold expansion

(R, G, B)=(20, 100, 40). At this time (Y, u, v)=(69, −14, −43)

If the image signals resulting when the flux of leakage light of 10 isadded to the image signals that have undergone the twofold expansion ofFormula (10) are transformed into Yuv space, then they are as shown inFormula (11).

(11) After taking flux of leakage light into consideration

(R, G, B)=(30, 110, 50). At this time (Y, u, v)=(79, −14, −4)

(12) Optical modulation (×½)

(R, G, B)=(15, 55, 25). At this time (Y, u, v)=(40, −7.2, −22)

Next, because there was an expansion factor of 2, if the image signalsof Formula (11) are modulated by ½ as their optical modulation (lightreduction, dimming) factor, then they are as shown in Formula (12).

As described above, because chromaticity can be expressed by(u²+v²)^(1/2)/Y in the case of Yuv space, the chromaticity predictionsection 34 predicts the chromaticity when expansion factor is 2 will beS₍₁₂₎=0.575.

A description will now be given of the chromaticity correction performedby the u signal correction section 330 and the v signal correctionsection 331. Chromaticity correction is a method of either loweringcolor space chromaticity to the chromaticity predicted for when there isno expansion, or raising the color space chromaticity to thechromaticity predicted for when there is an expansion.

Firstly, a description will be given of when correction is performed bymaking an adjustment to lower the chromaticity to S₍₂₎=0.510.

In the above Formula (10), if u′=−14×40/45=−13 and v′=−43×40/45=−38,then the image signals are as shown below.

(Y, u′, v′)=(69, −13, −38). At this time (R, G, B)=(26, 97, 43).

If this (R, G, B)=(26, 97, 43) is given a flux of leakage light of 10and an optical modulation factor of ½, then

(11′) After taking flux of leakage light into consideration

(R, G, B)=(36, 107, 53). At this time (Y, u, v)=(79, −13, −38)

(12′) Optical modulation (×½)

(R, G, B)=(18, 54, 45). At this time (Y, u, v)=(40, −6.4, −19).

With u=−6.4 and v=−19, then if the chromaticity is determined using(u²+v²)^(1/2)/Y, then S_((12′))=0.510. As a result, adjustment has beenmade to lower the chromaticity to 0.510.

Next, a description will be given of when correction is performed bymaking an adjustment to raise the chromaticity to S₍₁₂₎=0.575.

In the above Formula (7), if u₁=−7×45/40 and v₁=−22×45/40, then theimage signals are as shown below.

(Y, u₁, v₁)=(35, −8.1, −24). At this time (R, G, B)=(7, 52, 18).

If this (R, G, B)=(7, 52, 18) is given a flux of leakage light of 10 andan optical modulation factor of ½, then

(8′) After taking flux of leakage light into consideration

(R, G, B)=(17, 62, 28). At this time (Y, u, v)=(45, −8.1, −24).

With u=−8.1 and v=−24, then if the chromaticity is determined using(u²+v²)^(1/2)/Y, then S_((8′)=)0.575. As a result, adjustment has beenmade to raise the chromaticity to 0.575.

When transforming image signals into Yuv space and correctingchromaticity in this manner, because the transformation into Yuv spaceis made based on a predetermined formula (matrix), the transformation issimple and an increase in processing speed can be achieved.

FIG. 7 is a block diagram showing a variant example of the imageprocessing section 21 of FIG. 6. Note that the same numbers are given tocomponent elements that are identical to those appearing in FIG. 6, anda description thereof is omitted.

In the image processing section 21 shown in FIG. 7, a structure isemployed in which the expansion processing by the expansion section 31is only performed on Y signals of the Yuv space after transformationthereof by the image signal transformation section 32. Because expansionprocessing is performed only on Y signals, which indicate brightnessvalue information, it is possible to reduce the size of the circuitstructure, and further increase the processing speed.

The second embodiment will now be described. Note that the same numbersare given to component elements that are identical to those of the firstembodiment, and a description thereof is omitted.

FIG. 8 is a block diagram showing the structure of a drive circuit ofthe projection type display apparatus of the second embodiment.

In the drive circuit of the second embodiment, expansion coefficientsand offset values (offset quantity) are supplied from the image analysissection 24 to the image processing section 21. The term “offset values”refers to the darkest value among the image data. By subtracting theoffset value from the image signal when performing offset processing,unnecessary black floating can be suppressed in an image signal.

FIG. 9 is a block diagram showing the structure of the image processingsection 21 of the second embodiment when transforming image signals intoHSV space. Note that the same numbers are given to component elementsthat are identical to those of the image processing section of FIG. 3,and a description thereof is omitted.

As is shown in FIG. 9, the image processing section 21 is provided withan offset processing section 36, an expansion section 31, an imagesignal transformation section 32, a chromaticity correction section 33,a chromaticity prediction section 34, and a color space transformationsection 35. In addition, an offset processing section 36 has been addedin front of the expansion section 31 shown in FIG. 3.

The offset processing section 36 performs offset processing on imagesignals, that is, processing to subtract a predetermined subtractionquantity (i.e., offset value) from an image signal based on offsetvalues supplied from the image analysis section 24.

The expansion section 31 performs expansion processing on image signalsthat have completed offset processing.

The chromaticity prediction section 34 predicts chromaticity ofprojected image signals based on expansion coefficients supplied fromthe image analysis section 24, offset values, and quantities of escapedlight supplied from the memory/sensor section 201.

A description will now be given of the correction processing of theimage processing section 21 of the second embodiment when atransformation has been made into HSV space using specific numericalvalues. Here, as an example, a description is given of chromaticitycorrection when the image signals (R, G, B) are (10, 50, 20), the fluxof leakage light is 10, and the offset value is 5. It is assumed thatgamma valve is 1.0.

Firstly, when normal image signals are transformed into HSV space, theyare as is shown in Formula (13) below. Here, the chromaticity predictionsection 34 transforms image signals, to which the flux of leakage lightof 10 has been added, into HSV space, and predicts the chromaticity. Asis shown in Formula (14), here, the chromaticity is predicted to be 170.

(13) Original signal

(R, G, B)=(10, 50, 20). At this time (H, S, V)=(135, 204, 50).

(14) After taking flux of leakage light into consideration

(R, G, B)=(20, 60, 30). At this time (H, S, V)=(135, 170, 60).

Next, the chromaticity prediction section 34 predicts chromaticity foran image signal when the expansion coefficient is a twofold expansion.The image signal before the expansion can be expressed as is shown inFormula (15) to be the same as in Formula (13) above.

(15) Original signal

(R, G, B)=(10, 50, 20). At this time (H, S, V)=(135, 204, 50).

If the offset value of 5 is subtracted from this (R, G, B)=(10, 50, 20),then the result is as shown in Formula (16).

(16) Offset

(R, G, B)=(5, 45, 15). At this time (H, S, V)=(135, 227, 45).

If this (R, G, B)=(5, 45, 15) is expanded and given a flux of leakagelight of 10 and an optical modulation factor of ½ and gamma valve is1.0, then

(17) Expansion

(R, G, B)=(10, 90, 30). At this time (H, S, V)=(135, 227, 90).

(18) After taking flux of leakage light into consideration

(R, G, B)=(20, 100, 40). At this time (H, S, V)=(135, 204, 100).

(19) Optical modulation (×½)

(R, G, B)=(10, 50, 20). At this time (H, S, V)=(135, 204, 50).

As is shown in Formula (19), chromaticity is predicted to be 204.

Next, chromaticity correction by the chromaticity correction section 33when offset processing has been performed will be described.Chromaticity correction is a method of either lowering color spacechromaticity to the chromaticity predicted for when there is noexpansion, or raising the color space chromaticity to the chromaticitypredicted for when there is an expansion.

Firstly, a description will be given of when correction is performed bymaking an adjustment to lower the chromaticity to 170.

In the above Formula (17), if S′=170×227/204=189, then the image signalsare as shown below.

(H, S′, V)=(135, 189, 90). At this time (R, G, B)=(23, 90, 40).

If this (R, G, B)=(23, 90, 40) is given a flux of leakage light of 10and an optical modulation factor of ½, then

(18′) After taking flux of leakage light into consideration

(R, G, B)=(33, 100, 50). At this time (H, S, V)=(135, 170, 100)

(19′) Optical modulation (×½)

(R, G, B)=(17, 50, 25). At this time (H, S, V)=(135, 170, 50).

As is shown in Formula (19′), adjustment has been made to lower thechromaticity to 170.

Next, a description will be given of when correction is performed bymaking an adjustment to raise the chromaticity to 204.

In the above Formula (13), if S′=204×204/170=245, then the image signalsare as shown in Formula (13′).

(13′) Original signal

(H, S′, V)=(135, 245, 50). At this time (R, G, B)=(2, 50, 14).

If this (R, G, B)=(2, 50, 14) is given a flux of leakage light of 10 andan optical modulation factor of ½, then

(14′) After taking flux of leakage light into consideration

(R, G, B)=(12, 60, 24). At this time (H, S, V)=(135, 204, 60).

As is shown in Formula (14′), adjustment has been made to raise thechromaticity to 204.

By performing processing such as this, offset processing is performedbefore image signals are transformed into HSV space so that chromaticitycorrection is performed while black floating is being suppressed.

FIG. 10 is a block diagram showing a variant example of the imageprocessing section 21 shown in FIG. 9. Note that the same numbers aregiven to component elements that are identical to those of FIG. 9, and adescription thereof is omitted.

In the image processing section 21 of the variant example of the secondembodiment, a structure is employed in which the offset processing bythe offset processing section 36 and the expansion processing by theexpansion section 31 are only performed on V signals, which indicatebrightness value information after transformation by the image signaltransformation section 32.

Because offset processing and expansion processing are performed only onV signals, which indicate brightness value information, it is possibleto reduce the size of the circuit structure, and further increase theprocessing speed.

Note that, in the image processing section 21 of FIG. 9 or 10, astructure is employed in which the expansion section 31 is providedafter the offset processing section 36, however, the present embodimentis not limited to this. For example, it is also possible to use astructure in which the sequence is the expansion section 31 first andthen the offset processing section 36, and to then perform offsetprocessing on V signals, which indicate brightness value information, orRGB image signals after expansion processing.

FIG. 11 is a block diagram showing the structure of the image processingsection 21 of the second embodiment when image signals are transformedinto Yuv space. Note that the same numbers are given to componentelements that are identical to those appearing in FIGS. 6 and 9, and adescription thereof is omitted.

As is shown in FIG. 11, the image processing section 21 is provided withan offset processing section 36, an expansion section 31, an imagesignal transformation section 320, a u signal correction section 330, av signal correction section 331, a chromaticity prediction section 34,and a color space transformation section 350. The offset processingsection 36 has been added in front of the expansion section 31 shown inFIG. 6.

A description will now be given of the correction processing of theimage processing section 21 of the second embodiment when atransformation has been made into Yuv space using specific numericalvalues. Here, as an example, a description is given of chromaticitycorrection when the image signals (R, G, B) are (10, 50, 20), the fluxof leakage light is 10, and the offset value is 5.

Firstly, when normal image signals are transformed into Yuv space basedon Formula group A, they are as is shown in Formula (20) below. Here, ifthe image signals to which the flux of leakage light of 10 has beenadded are also transformed into Yuv space based on Formula group A, thenthey are as is shown in Formula (21).

(20) Original signal

(R, G, B)=(10, 50, 20). At this time (Y, u, v)=(35, −7.2, −22).

(21) After taking flux of leakage light into consideration

(R, G, B)=(20, 60, 30). At this time (Y, u, v)=(45, −7.2, −22).

For Yuv space, as is shown by Formula group A, the chromaticity isexpressed by (u²+v²)^(1/2)/Y. Therefore, the chromaticity predictionsection 34 predicts that the chromaticity with the flux of leakage lighttaken into consideration will be S₍₂₁₎=0.510.

Next, the chromaticity prediction section 34 predicts chromaticity foran image signal when the expansion coefficient is an expansion factor of2. The image signal before the expansion can be expressed as is shown inFormula (22) to provide the same result as Formula (20) above.

(22) Original signal

(R, G, B)=(10, 50, 20). At this time (Y, u, v)=(35, −7.2, −22).

If the offset value of 5 is subtracted from this (R, G, B)=(10, 50, 20),then the result is as shown in Formula (23).

(23) Offset

(R, G, B)=(5, 45, 15). At this time (Y, u, v)=(29, −7.2, −22).

If this (R, G, B)=(5, 45, 15) is expanded, given a flux of leakage lightof 10 and an optical modulation factor of ½, then

(24) Expansion

(R, G, B)=(10, 90, 30). At this time (Y, u, v)=(59, −14, −43).

(25) After taking flux of leakage light into consideration

(R, G, B)=(20, 100, 40). At this time (Y, u, v)=(69, −14, −43).

(26) Optical modulation (×½)

(R, G, B)=(10, 50, 20). At this time (Y, u, v)=(35, −7.2, −22).

As shown above, for Yuv space the chromaticity is expressed by(u²+v²)^(1/2)/Y. Therefore, the chromaticity prediction section 34predicts that the chromaticity when there has been a twofold expansionwill be S₍₂₆₎=0.658.

A description will now be given of the chromaticity correction performedby the u signal correction section 330 and the v signal correctionsection 331 when offset processing is performed. Chromaticity correctionis a method of either lowering color space chromaticity to thechromaticity predicted for when there is no expansion, or raising thecolor space chromaticity to the chromaticity predicted for when there isan expansion.

Firstly, a description will be given of when correction is performed bymaking an adjustment to lower the chromaticity to S₍₂₁₎=0.510.

In the above Formula (24), if u′=−14×35/45=−11 and v′=−43×35/45=−34,then the image signals are as shown below.

(Y, u′, v′)=(59, −11, −34). At this time (R, G, B)=(21, 83, 36).

If this (R, G, B)=(21, 83, 36) is given a flux of leakage light of 10and an optical modulation factor of ½, then

(25′) After taking flux of leakage light into consideration

(R, G, B)=(31, 93, 46). At this time (Y, u, v)=(69, −11, −34)

(26′) Optical modulation (×½)

(R, G, B)=(16, 47, 23). At this time (Y, u, v)=(35, −5.6, −17).

With u=−5.6 and v=−17, then if the chromaticity is determined using(u²+v²)^(1/2)/Y, then S_((26′))=0.510. As a result, adjustment has beenmade to lower the chromaticity to 0.510.

Next, a description will be given of when correction is performed bymaking an adjustment to raise the chromaticity to S₍₂₆₎=0.658.

In the above Formula (20), if u′=−7×45/35=−9.3 and v′=−22×45/35=−28,then the image signals are as shown below.

(20′) Original signal

(Y, u′, v′)=(35, −9.3, −28). At this time (R, G, B)=(3, 54, 16).

(21′) After taking flux of leakage light into consideration

(R, G, B)=(13, 64, 26). At this time (Y, u, v)=(45, −9.3, −28).

With u=−9.3 and v=−28, then if the chromaticity is determined using(u²+v²)^(1/2)/Y, then S_((21′))=0.658. As a result, adjustment has beenmade to raise the chromaticity to 0.658.

By performing processing such as this, offset processing is performedbefore image signals are transformed into Yuv space so that chromaticitycorrection can be performed while black floating is being suppressed.

FIG. 12 is a block diagram showing a variant example of the imageprocessing section 21 shown in FIG. 11. Note that the same numbers aregiven to component elements that are identical to those of FIG. 11, anda description thereof is omitted.

In the image processing section 21 of the variant example of the secondembodiment, a structure is employed in which the offset processing bythe offset processing section 36 and the expansion processing by theexpansion section 31 are only performed on Y signals, which indicatebrightness information after transformation by the image signaltransformation section 32.

Because offset processing and expansion processing are performed only onY signals, which indicate brightness information, it is possible toreduce the size of the circuit structure, and further increase theprocessing speed.

Note that, in the image processing section 21 of FIG. 11 or 12, astructure is employed in which the expansion section 31 is providedafter the offset processing section 36, however, the present embodimentis not limited to this. For example, it is also possible to use astructure in which the sequence is the expansion section 31 first andthen the offset processing section 36, and to then perform offsetprocessing on Y signals, which indicate brightness value information, orRGB image signals after expansion processing.

Next, a description is given of when the image processing section 21itself calculates color correction directly based on a predeterminedcalculation formula.

FIG. 13 is a block diagram showing the structure of the image processingsection 21 of the third embodiment. The image processing section 21 isprovided with calculation sections 370, 371, and 372 that make colorcorrections of R signals, G signals, and B signals.

The image processing section 21 of the third embodiment makes colorcorrections of the respective RGB colors by direct calculation using thecalculation sections 370, 371, and 372 without performing color spacetransformation on the image signals such as is described in the firstand second embodiments.

Here, the calculation formula employed by the calculation sections 370,371, and 372 of the image processing section 21 of the third embodimentwill be described. As an example, a description is given of when theflux of leakage light is δv and the offset value is v₀. The image on thescreen are written (R₀, G₀, B₀)=(r₀+δv, g₀+δv, b₀+δv). The displayedimage after 1/p optical modulation and expansion by a factor of p can beexpressed as is shown below.(R ₁ , G ₁ , B ₁)=(r ₁ −v ₀ +δv/p, g ₁ −v ₀ +δv/p, b ₁ −v ₀ +δv/p)

Here, when a correction calculation is performed to lower the colorvividness, the calculation sections 370, 371, and 372 control thesignals r₁′, g₁′, b₁′ so as to satisfy the next condition,

$\begin{matrix}{\left( {R_{1}^{\prime}\text{:}G_{1}^{\prime}\text{:}B_{1}^{\prime}} \right) = \left( {r_{1}^{\prime} - v_{0} + {\delta\;{v/p}\text{:}g_{1}^{\prime}} - v_{0} + {\delta\;{v/p}\text{:}b_{1}^{\prime}} - v_{0} + {\delta\;{v/p}}} \right)} \\{= \left( {R_{0}\text{:}G_{0}\text{:}B_{0}} \right)} \\{= \left( {r_{0} + {\delta\; v\text{:}g_{0}} + {\delta\; v\text{:}b_{0}} + {\delta\; v}} \right)}\end{matrix}$

When a correction calculation is performed to raise the color vividness,the calculation sections 370, 371, and 372 control the signals r₀′, g₀′,b₀′ in the same way such that

$\begin{matrix}{\left( {R_{1}^{\prime}\text{:}G_{1}^{\prime}\text{:}B_{1}^{\prime}} \right) = \left( {r_{1}^{\prime} - v_{0} + {\delta\;{v/p}\text{:}g_{1}^{\prime}} - v_{0} + {\delta\;{v/p}\text{:}b_{1}^{\prime}} - v_{0} + {\delta\;{v/p}}} \right)} \\{= \left( {R_{0}^{\prime}\text{:}G_{0}^{\prime}\text{:}B_{0}^{\prime}} \right)} \\{= \left( {r_{0}^{\prime} + {\delta\; v\text{:}g_{0}^{\prime}} + {\delta\; v\text{:}b_{0}^{\prime}} + {\delta\; v}} \right)}\end{matrix}$

In this way, because the image processing section 21 of the thirdembodiment performs color correction by direct calculation based on apredetermined calculation formula without transforming RGB image signalsinto the other color space, the processing speed can be increased by thelength of time hitherto consumed by the transformation processing.

The fourth embodiment will now be described. Note that the same numbersare given to component elements that are identical to those of the firstand second embodiments, and a description thereof is omitted.

FIG. 14 is a block diagram showing the structure of a driver of theprojection type display apparatus of the fourth embodiment. In thedriver of the fourth embodiment expansion coefficients are supplied tothe image processing section 21 from the image analysis section 24 inthe form of transformation tables. In the fourth embodiment, the imageprocessing section 21 calculates offset values and main expansioncoefficients from expansion coefficients provided by a transformationtable such as that shown in FIG. 15. The image processing section 21then predicts color vividness (chromaticity) from the calculated valuesand the flux of leakage light. Note that the horizontal axis of thetransformation table in FIG. 15 represents input image signals, whilethe vertical axis represents image signals after their transformation.

FIG. 16 is a block diagram showing the structure of the image processingsection 21 of the fourth embodiment when a transformation table is used.

As is shown in FIG. 16, the image processing section 21 is provided withtransformation processing sections 380, 381, and 382 that performtransformations and expansions based on a transformation table,correction calculation sections 3701, 3711, and 3721, and a coefficientseparation section 39.

The transformation processing section 380 performs offset processing andexpansion processing on R signals from among the image signals based ona transformation table (a look up table; LUT) supplied from the imageanalysis section 24. In the same way, the transformation processingsection 381 performs offset processing and expansion processing on Gsignals from among the image signals, and the transformation processingsection 382 performs offset processing and expansion processing on Bsignals.

The coefficient separation section 39 separates expansion coefficientsand offset values from a transformation table supplied from the imageanalysis section 24, and supplies them to the respective correctioncalculation sections 3701, 3711, and 3721 for RGB signals.

The correction calculation section 3701 performs chromaticity correctionof R signals based on offset values and expansion coefficients suppliedfrom the transformation processing section 380, expansion coefficientsand offset values supplied from the coefficient separation section 39,and fluxes of leakage light supplied from the memory/sensor section 201.The chromaticity correction by the correction calculation section 3701is performed based on the predetermined calculation formula described inthe third embodiment. In the same way, the correction calculationsection 3711 performs chromaticity correction on G signals, and thecorrection calculation section 3721 performs chromaticity correction onB signals.

FIG. 17 is a block diagram showing the structure of the image processingsection 21 of the fourth embodiment when the RGB signals are transformedinto HSV space. Note that the same numbers are given to componentelements that are identical to those of the first, second and thirdembodiments, and a description thereof is omitted.

As is shown in FIG. 17, the image processing section 21 is provided witha transformation processing section 37 that performs expansions andtransformations based on transformation tables, an image signaltransformation section 32, a chromaticity correction section 33, achromaticity prediction section 34, a color space transformation section35, and a coefficient separation section 39.

The transformation processing section 37 performs expansion processingand offset processing on input image signals based on transformationtables supplied from the image analysis section 24.

The image signal transformation section 21 transforms image signals thathave undergone expansion processing and offset processing by thetransformation processing section 37 into the HSV space form of colorspace.

The coefficient separation section 39 supplies offset values andexpansion coefficients that have been separated from the transformationtable supplied from the image analysis section 24 to the chromaticityprediction section 34.

The chromaticity prediction section 34 predicts chromaticity ofprojected image signals based on expansion coefficients and offsetvalues supplied from the coefficient separation section 39, and onquantities of escaped light supplied from the memory/sensor section 201.

FIG. 18 is a block diagram showing a variant example of the imageprocessing section 21 shown in FIG. 17. Note that the same numbers aregiven to component elements that are identical to those of FIG. 17, anda description thereof is omitted.

In the image processing section 21 of the variant example of the fourthembodiment, a structure is employed in which the offset processing andexpansion processing by the transformation processing section 37 basedon transformation tables is only performed on V signals, which representbrightness value information after the transformation by the imagesignal transformation section 32.

In this way, because offset processing and expansion processing based ontransformation tables are only performed on V signals representingbrightness value information, the size of the circuit structure can bereduced and the processing speed increased.

In the image processing sections 21 of FIGS. 16 through 18 complicatedexpansion processing becomes possible and the image representation widthcan be broadened by using transformation tables.

FIG. 19 is a block diagram showing the structure of a drive circuit whenencoded image signals are input. Note that the same numbers are given tocomponent elements that are identical to those of the drive circuitshown in FIG. 2, and a description thereof is omitted.

In the drive circuit in FIG. 19, a decoder 27 that decodes encoded imagesignals has been added to the drive circuit shown in FIG. 2. The decoderdecodes encoded signals and supplies decoded image signals to the imageprocessing section 21.

Note that the image processing section 21 of FIG. 19 can be providedwith the same structure as those described in the above first throughfourth embodiments and in the variant examples of each embodiment.

FIG. 20 is a diagram showing a variant example of the structure shown inFIG. 19. Note that the same numbers are given to component elements thatare identical to those of FIG. 19, and a description thereof is omitted.

In the drive circuit shown in FIG. 20, the decoder 27 decodes imagesignals on which predetermined image processing has been performed bythe image processing section 21. That is, encoded image signals areinput into the image processing section 21. Note that, in the same wayas for FIG. 19, the image processing section 21 of FIG. 20 can beprovided with the same structure as those described in the above firstthrough fourth embodiments and in the variant examples of eachembodiment.

An embodiment of the present invention has been described above;however, the present invention is not limited to the above describedembodiment.

For example, in the selection of correction parameters, the abovedescription is of when a user sets correction parameters using theconsole section 202, and the selection can be made between lowering orraising a chromaticity, however, the present embodiment is not limitedto this. For example, in the console section 202, it is also possible toemploy a structure in which a user can optionally make a setting thatallows chromaticity to be set in the middle of the values predicted bythe chromaticity prediction section 34.

For example, in the present embodiment, a description is given of when aprojection type display apparatus is used as an image display apparatuscapable of utilizing a computer-readable recording medium storing theimage display program and image display method of the present invention,however, the present embodiment is not limited to this, and it is alsopossible, for example, for a direct view display apparatus to be used.

Furthermore, the computer-readable recording medium storing the imagedisplay program and image display method of the present invention mayalso be used for processing image signals such as those of LCDs,electroluminescence display, plasma displays, digital mirror devices,field emission devices, and the like.

While preferred embodiments of the invention have been described andillustrated above, it should be understood that these are exemplary ofthe invention and are not to be considered as limiting. Additions,omissions, substitutions, and other modifications can be made withoutdeparting from the spirit or scope of the present invention.Accordingly, the invention is not to be considered as being limited bythe foregoing description, and is only limited by the scope of theappended claims.

1. An image display apparatus that adjusts a displayed image by changinga flux of light, comprising: an image signal transformation device thattransforms a brightness level of image signals of a plurality of primarycolors of a displayed image into a color space that includes achromaticity and a lightness; a prediction device that predicts achromaticity of the color space when the flux of light is changed; acorrection device that corrects the chromaticity in the color space thathas been transformed by the image signal transformation device, inaccordance with a prediction made by the prediction device; an expansiondevice that expands the lightness in the color space that has beentransformed by the image signal transformation device; and a color spacetransformation device that transforms the color space that includes thelightness expanded by the expansion device and the correctedchromaticity into image signals of a plurality of primary colors; and animager that is controlled in accordance with the image signals outputtedby the color space transformation device.
 2. The image display apparatusaccording to claim 1, further comprising: an optical modulator that iscontrolled in accordance with the expansion of the lightness by theexpansion device.
 3. The image display apparatus according to claim 1,further comprising: a detecting device that detects a flux of leakagelight from the imager.
 4. An image display apparatus that adjusts adisplayed image by changing a flux of light, comprising: a correctiondevice that performs correction of an original chromaticity andexpansion of an original brightness level of image signals based on apredetermined calculation formula for each image signal of a pluralityof primary colors of a displayed image, in accordance with a predictionof chromaticity of the displayed image when the flux of light ischanged; and an imager that is controlled in accordance with the imagesignals outputted by the correction device.
 5. The image displayapparatus according to claim 4, further comprising: an optical modulatorthat is controlled in accordance with the expansion of the brightness bythe correction device.
 6. The image display apparatus according to claim4, further comprising: a detecting device that detects a flux of leakagelight from the imager.
 7. A computer-readable recording medium storingan image display program which adjusts a displayed image displayed by animage display apparatus, by changing a flux of light, the programexecutable on a computer, the program performing: an image signaltransformation function that transforms image signals of a plurality ofprimary colors of a displayed image into a color space that includes achromaticity and a lightness; a chromaticity prediction function thatpredicts a chromaticity of the color space when the flux of light ischanged; a correction function that corrects the chromaticity in thecolor space that has been transformed by the image signal transformationfunction, in accordance with a prediction made in the chromaticityprediction function; an expansion function that expands the lightness inthe color space that has been transformed by the image signaltransformation function; and a color space transformation function thattransforms the color space that includes the lightness expanded by theexpansion function and the corrected chromaticity into image signals ofa plurality of primary colors.
 8. A computer-readable recording mediumstoring an image display program which adjusts a displayed imagedisplayed by an image display apparatus, by changing a flux of light,the program executable on a computer, the program performing: acorrection function that performs correction of an original chromaticityand expansion of an original brightness level of image signals based ona predetermined calculation formula for respective image signals of aplurality of primary colors of the displayed image, in accordance with aprediction of chromaticity of the displayed image when the flux of lightis changed.